As a result, many retailers likely will report solid results for the fourth quarter and the overall economy could get a decent boost from that.

The down side: But low oil prices are also wreaking havoc on the economies of countries that depend on the commodity, most notably Russia.

There are also fears that persistently lower gas prices could lead to a slowdown in drilling in the United States. Some experts have argued that $30 oil is possible. Rystad Energy estimates that oil needs to stay above $58 a barrel for America's shale plays to breakeven.

That could mean big layoffs in an industry that has been adding many jobs over the past few years. There have already been a few thousand job cuts announced, including from Halliburton(HAL).

Investors have also grown more nervous about what the slide in oil prices might mean for the global economy.

The Dow plunged 300 points Monday, with energy stocks Chevron(CVX) and Exxon Mobil(XOM) as well as cyclical companies General Electric(GE) and Caterpillar(CAT) taking some of the bigger hits.